In a mobile communication system of an LTE (Long Term Evolution) scheme, it is defined only that a radio base station HeNB#1 or HeNB#3 which manages handover source cells performs only an S1 handover as a method for achieving a handover of a mobile station UE.
However, even in this case, an X2 handover may be performed under the conditions that the X2 handover can be performed.
For example, the X2 handover can be performed between cells operated in “Closed Mode” operated where a connection of only a mobile station of a particular subscriber is allowed by an owner of the radio base station HeNB, and between the cells subordinate to radio base stations HeNB with the same “Closed Subscriber Group ID (CSG-ID)” which are the identifiers to designate the particular subscriber.
Alternately, the X2 handover can be performed between the cells subordinate to radio base stations HeNB operated in “Open Mode” where connectable mobile stations are not limited.
Furthermore, the X2 handover can be performed between cells subordinate to radio base stations HeNB operated in “Hybrid Mode”, where the “Closed Mode” and the “Open Mode” are simultaneously operated, which is Access Mode where priority control operations different between the mobile stations belonging to a specific CSG and the mobile stations not belonging to the specific CSG are performed, between the cells subordinate to the radio base stations with the same CSG operated in the “Closed Mode”, or between the cells subordinate to the radio base stations HeNB operated in the “Open Mode”.
The mobile communication system of the existing LTE scheme, however, has a problem in that each radio base station HeNB does not manage Access Mode and CSG-ID (Closed Subscriber Group) of the cell subordinate to a neighboring radio base station HeNB, and therefore, as illustrated in FIG. 12, the radio base station HeNB#1 or HeNB#3 cannot consider Access Mode and CSG-ID of the cell subordinate to the radio base station HeNB#2 at the time of deciding the method (the X2 handover or the S1 handover) for achieving the handover of the mobile station UE from the cell subordinate to the radio base station HeNB#1 or HeNB#3 to the cell subordinate to the radio base station HeNB#2.